The proposed research seeks to capitalize upon the extensive morphological and functional interconnections among olfactory, limbic and basal forebrain structures in rodents to develop an advantageous model for studies of aging in the mammalian central nervous system. Neurochemical changes in limbic and cholinergic basal forebrain structures with which the olfactory system is directly connected have been implicated as etiological factors in mnemonic and cognitive impairments that sometimes occur with aging, and more severe atrophic changes in these structures and connections may account for debilitating symptoms of Alzheimer's disease. An interrelated series of psychophysical, behavioral, electrophysiological, endocrinological, biochemical and immunohistochemical analyses is proposed to examine the effects of aging changes in these structures and connections on cognitive and mnemonic aspects of olfactory information processing. Through these analyses we hope to lay the groundwork for research on cellular and neurochemical mechanisms of brain aging.